Version:            (using KDE 4.2.1)
OS:                Linux
Installed from:    Debian testing/unstable Packages

I got this when I hit the top edge of the screen, where I've configured the Present Windows effect to be activated.

Program: Kwin (kwin), signal SIGSEGV
0x00007fa3c82a88a0 in __nanosleep_nocancel () from /lib/libc.so.6
Current language:  auto; currently c

Thread 1 (Thread 0x7fa3c88fe760 (LWP 5312)):
[KCrash Handler]
#5  0x00000000006f1a40 in ?? ()
#6  0x00007fa3be32f3e3 in KWin::PresentWindowsEffect::setHighlightedWindow (this=0x757a80, w=0x8cb670) at ../../../kwin/effects/presentwindows.cpp:1270
#7  0x00007fa3be33a3df in KWin::PresentWindowsEffect::rearrangeWindows (this=0x757a80) at ../../../kwin/effects/presentwindows.cpp:487
#8  0x00007fa3be33af11 in KWin::PresentWindowsEffect::setActive (this=0x757a80, active=<value optimized out>, closingTab=<value optimized out>) at ../../../kwin/effects/presentwindows.cpp:1153
#9  0x00007fa3be33b835 in KWin::PresentWindowsEffect::borderActivated (this=0x757a80, border=KWin::ElectricTop) at ../../../kwin/effects/presentwindows.h:99
#10 0x00007fa3c85f7994 in KWin::EffectsHandlerImpl::borderActivated (this=<value optimized out>, border=KWin::ElectricTop) at ../../kwin/effects.cpp:321
#11 0x00007fa3c858765c in KWin::Workspace::checkElectricBorder (this=0x70e080, pos=@0x7fffd0a36fe0, now=6657451) at ../../kwin/workspace.cpp:2260
#12 0x00007fa3c858775f in KWin::Workspace::electricBorderEvent (this=0x70e080, e=0x7fffd0a37980) at ../../kwin/workspace.cpp:2324
#13 0x00007fa3c85aa83a in KWin::Workspace::workspaceEvent (this=0x70e080, e=0x7fffd0a37980) at ../../kwin/events.cpp:475
#14 0x00007fa3c8598aa8 in KWin::Application::x11EventFilter (this=0x7fffd0a37d70, e=0x7fffd0a37980) at ../../kwin/main.cpp:359
#15 0x00007fa3c531196f in qt_x11EventFilter (ev=0x7fffd0a37980) at kernel/qapplication_x11.cpp:375
#16 0x00007fa3c5324d8f in QApplication::x11ProcessEvent (this=0x7fffd0a37d70, event=0x7fffd0a37980) at kernel/qapplication_x11.cpp:3273
#17 0x00007fa3c534dee4 in x11EventSourceDispatch (s=0x60e350, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#18 0x00007fa3c1ab1afb in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#19 0x00007fa3c1ab52bd in ?? () from /usr/lib/libglib-2.0.so.0
#20 0x00007fa3c1ab547b in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#21 0x00007fa3c4b9b29f in QEventDispatcherGlib::processEvents (this=0x6071d0, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:323
#22 0x00007fa3c534d68f in QGuiEventDispatcherGlib::processEvents (this=0x6e6560, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:202
#23 0x00007fa3c4b704f2 in QEventLoop::processEvents (this=<value optimized out>, flags={i = -794592144}) at kernel/qeventloop.cpp:149
#24 0x00007fa3c4b708bd in QEventLoop::exec (this=0x7fffd0a37cb0, flags={i = -794592064}) at kernel/qeventloop.cpp:200
#25 0x00007fa3c4b72b84 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:880
#26 0x00007fa3c859c31f in kdemain (argc=3, argv=0x7fffd0a38248) at ../../kwin/main.cpp:519
#27 0x00007fa3c82285a6 in __libc_start_main (main=0x4006f0 <main>, argc=3, ubp_av=0x7fffd0a38248, init=0x400720 <__libc_csu_init>, fini=<value optimized out>, rtld_fini=<value optimized out>, 
    stack_end=0x7fffd0a38238) at libc-start.c:222
#28 0x0000000000400629 in _start () at ../sysdeps/x86_64/elf/start.S:113